WPF cvs draw rectangle and line

  1 //xaml
  2 <Window x:Class="WpfApp67.MainWindow"
  3         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  4         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  5         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
  6         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
  7         WindowState="Maximized"
  8         xmlns:local="clr-namespace:WpfApp67"
  9         mc:Ignorable="d"
 10         Title="MainWindow" Height="450" Width="800">
 11     <Grid>
 12         <Grid.RowDefinitions>
 13             <RowDefinition/>
 14             <RowDefinition Height="50"/>
 15         </Grid.RowDefinitions>
 16         <Canvas x:Name="cvs"
 17                 Grid.Row="0"
 18                 Background="Transparent"
 19                 PreviewMouseDown="cvs_PreviewMouseDown"
 20                 PreviewMouseUp="cvs_PreviewMouseUp"
 21                 PreviewMouseMove="cvs_PreviewMouseMove">
 22             <!--<Rectangle x:Name="rect"
 23                        Visibility="Collapsed"
 24                        Fill="LightBlue"
 25                        Stroke="DarkBlue"
 26                        StrokeThickness="5">                
 27             </Rectangle>-->
 28         </Canvas>
 29         <StatusBar Grid.Row="1">
 30             <StatusBarItem>
 31                 <TextBlock x:Name="statusTbk"
 32                            FontSize="20"/>
 33             </StatusBarItem>
 34         </StatusBar>
 35     </Grid>
 36 </Window>
 37 
 38 
 39 
 40 
 41 //cs
 42 using System;
 43 using System.Collections.Generic;
 44 using System.Linq;
 45 using System.Text;
 46 using System.Threading.Tasks;
 47 using System.Windows;
 48 using System.Windows.Controls;
 49 using System.Windows.Data;
 50 using System.Windows.Documents;
 51 using System.Windows.Input;
 52 using System.Windows.Media;
 53 using System.Windows.Media.Imaging;
 54 using System.Windows.Navigation;
 55 using System.Windows.Shapes;
 56 
 57 namespace WpfApp67
 58 {
 59     /// <summary>
 60     /// Interaction logic for MainWindow.xaml
 61     /// </summary>
 62     public partial class MainWindow : Window
 63     {
 64         private Point startPt, endPt;
 65         string statusMsg = string.Empty;
 66         int idx = 0;
 67         List<Rectangle> rectsList = new List<Rectangle>();
 68 
 69         List<Line> linesList = new List<Line>();
 70 
 71         public MainWindow()
 72         {
 73             InitializeComponent();
 74         }
 75 
 76         private void cvs_PreviewMouseDown(object sender, MouseButtonEventArgs e)
 77         {
 78             startPt = e.GetPosition(cvs);
 79             rectsList.Add(new Rectangle());
 80             linesList.Add(new Line());
 81         }
 82 
 83         private void cvs_PreviewMouseUp(object sender, MouseButtonEventArgs e)
 84         {
 85             if (!cvs.Children.Contains(rectsList[idx]))
 86             {
 87                 rectsList[idx].ToolTip = $"Rect[{idx+1}],{Guid.NewGuid().ToString("N")}";
 88                 cvs.Children.Add(rectsList[idx]);
 89             }
 90             if (!cvs.Children.Contains(linesList[idx]))
 91             {
 92                 linesList[idx].ToolTip = $"Line[{idx + 1}],{Guid.NewGuid().ToString("N")}";
 93                 cvs.Children.Add(linesList[idx]);
 94             }
 95             ++idx;
 96         }
 97 
 98         private void cvs_PreviewMouseMove(object sender, MouseEventArgs e)
 99         {
100             if (Mouse.LeftButton == MouseButtonState.Pressed)
101             {
102                 endPt = e.GetPosition(cvs);
103                 Rectangle rect = rectsList[idx];
104                 rect.Stroke = new SolidColorBrush(Colors.DarkBlue);
105                 rect.StrokeThickness = 5;
106                 rect.Visibility = Visibility.Visible;
107                 rect.Width = Math.Abs(endPt.X - startPt.X);
108                 rect.Height = Math.Abs(endPt.Y - startPt.Y);
109                 Canvas.SetLeft(rect, startPt.X);
110                 Canvas.SetTop(rect, startPt.Y);
111 
112 
113                 Line ln = linesList[idx];
114                 ln.X1 = startPt.X+2.5;
115                 ln.Y1 = startPt.Y+2.5;
116                 ln.X2 = endPt.X-2.5;
117                 ln.Y2 = endPt.Y-2.5;
118                 ln.Stroke = new SolidColorBrush(Colors.DarkBlue);
119                 ln.StrokeThickness = 1;
120               
121                 statusMsg = $"Start:({startPt.X},{startPt.Y}),end point:({endPt.X},{endPt.Y})";
122                 UpdateStatus(statusMsg);
123                 if (!cvs.Children.Contains(rectsList[idx]))
124                 {
125                     cvs.Children.Add(rectsList[idx]);
126                 }
127                 if (!cvs.Children.Contains(linesList[idx]))
128                 {
129                     cvs.Children.Add(linesList[idx]);
130                 }
131             }
132         }
133 
134         private void UpdateStatus(string msg)
135         {
136             Application.Current.Dispatcher.Invoke(new Action(() =>
137             {
138                 statusTbk.Text = msg;
139             }));
140         }
141     }
142 }